Fuel sending unit calibration

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plymouth71

plymouth71

The Moomobile
Joined
Jun 6, 2010
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London ky
Could anybody tell me the best way to calibrate the sending unit to the fuel gauge on a 71 scamp,I have tried twice but can't seem to get it right,any help would be appreciated
 
Thanks,a lot of good info here,I will try some of the tests as soon as weather permits.I bought a new sender from classic ind and I thought I had it exact to original but it reads almost 1/2 tank off.I honestly didn't think it would have giving me so much trouble
 
The short answer seems to be that nobody makes a good accurate replacement sender. Your options seem to be

1...Fix clean and use the old one

2...Get real lucky and find a NOS for less than your first born

3...Figure out how to bend,adjust, and use the repop stuff, possibly with the calibration box posted above.

For me? I'd just be happy to have "some idea" of having "low" and "empty" accurate enough to drive.
 
You are right,I will try some trial and error and let you know what I find out,Thanks for your help.
 
I'm having the same issue, as I tweek the float I get some change but still over 1/3 tank off. I'll let you know if and how I make out.
 
Quality control on today's gauges is different. If the ohms read 73 on the EMPTY stop and 10 on the FULL stop, it passes. They are not checked through the full range as they were in the past. So, the sender could reach full or empty anywhere in the swing. No bending of the float arm will fix this. So, it's really a crap shoot when buying one.
 
I seen a unit that classic ind has for $100 but it looks like a repop,year 1 has a unit that is suppose to be a brand new mopar unit for$139 but I'm a little hesitant on both,hate to shell out Good money and end up no better off than I am.I think I will check around some more
 
I just located a nos sending unit, issue is the guy wants an arm & leg for it. I may bite the bullet on it to see if it solves the issue. I wont get a chance to put it in till spring, so I'm hoping someone finds a cheaper fix in the mean time.
 
Mr.FT said:
I just located a nos sending unit, issue is the guy wants an arm & leg for it. I may bite the bullet on it to see if it solves the issue. I wont get a chance to put it in till spring, so I'm hoping someone finds a cheaper fix in the mean time.
Click to expand...
I may try the unit from year 1,like you I won't be able to install until spring,hopefully this will fix the problem,will post again when I find out
 
I always bend the sendin unit arm. Is this a trick question?
 
Too bad the vendors won't put the time into building a quality sending unit. The units in the past were. Shouldn't have to calibrate them or try to make them work. That should be done at the factory. Just lazy.
 
bruceo2011 said:
Too bad the vendors won't put the time into building a quality sending unit. The units in the past were. Shouldn't have to calibrate them or try to make them work. That should be done at the factory. Just lazy.
Click to expand...
Agreed,it would save a lot of time,work and headaches,not to mention a lot of money
 
RustyRatRod said:
I always bend the sendin unit arm. Is this a trick question?
Click to expand...
Not a trick question,I have tried bending the float arm,and tried bending the stop tabs.No matter what I do it always shows half a tank off.It could be I got a hold of a bad sender.I tested the gauge and it is good,checked wiring from gauge to tank,all good,it's been a pure headache.
 
You need to make sure your sending unit reads the same ohms full and empty that the gauge does. Sounds like there is a mismatch.
 
plymouth71 said:
Not a trick question,I have tried bending the float arm,and tried bending the stop tabs.No matter what I do it always shows half a tank off.It could be I got a hold of a bad sender.I tested the gauge and it is good,checked wiring from gauge to tank,all good,it's been a pure headache.
Click to expand...

What I do is test them before installing in the tank. I hook it up to the connector at the tank and ground it. I have someone watch the gauge as I slowly run it through it's range. Start at the FULL position, stop at 3/4, then 1/2, then 1/4 and finally at EMPTY. Then I check by gauge position and note where the float arm is when the gauge reads FULL, 3/4,1/2,1/4 and finally EMPTY. It is amazing to see how bad some sending units are. It's putsy work, but beats installing it and finding out it's junk.
 
Most aftermarket sending units are wound with a linear resister. Since our A body's have the spare tire recess in the upper portion of the tank, the factory used a non- linear resister on the sending units. No amount of bending the arm will ever get the gauge to read properly. Either a electric/computer device to compensate or a aftermarket company coming up with the proper non-linear sending unit. even if some one come up with the proper resister and we installing it on our older sending units would be nice.
 
bruceo2011 said:
What I do is test them before installing in the tank. I hook it up to the connector at the tank and ground it. I have someone watch the gauge as I slowly run it through it's range. Start at the FULL position, stop at 3/4, then 1/2, then 1/4 and finally at EMPTY. Then I check by gauge position and note where the float arm is when the gauge reads FULL, 3/4,1/2,1/4 and finally EMPTY. It is amazing to see how bad some sending units are. It's putsy work, but beats installing it and finding out it's junk.
Click to expand...
I did everything you suggested but I didn't have any help,I tried to watch the gauge as I moved the float arm,at the angle I was sitting I may have been looking at the gauge wrong,I will try it again but with help this time.Thanks for the input,I will try again soon.
 
Well my buddy found me a nos fuel sending unit for the Demon. Santa helped deliver it to me, come on spring so I can see if it solves my fuel gauge issues.
 
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